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credrequest.go
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credrequest.go
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/*
Copyright IBM Corp. All Rights Reserved.
SPDX-License-Identifier: Apache-2.0
*/
package bridge
import (
"bytes"
"github.com/golang/protobuf/proto"
"github.com/hyperledger/fabric-amcl/amcl"
"github.com/hyperledger/fabric/bccsp/idemix/handlers"
cryptolib "github.com/hyperledger/fabric/idemix"
"github.com/pkg/errors"
)
// CredRequest encapsulates the idemix algorithms to produce (sign) a credential request
// and verify it. Recall that a credential request is produced by a user,
// and it is verified by the issuer at credential creation time.
type CredRequest struct {
NewRand func() *amcl.RAND
}
// Sign produces an idemix credential request. It takes in input a user secret key and
// an issuer public key.
func (cr *CredRequest) Sign(sk handlers.Big, ipk handlers.IssuerPublicKey, nonce []byte) (res []byte, err error) {
defer func() {
if r := recover(); r != nil {
res = nil
err = errors.Errorf("failure [%s]", r)
}
}()
isk, ok := sk.(*Big)
if !ok {
return nil, errors.Errorf("invalid user secret key, expected *Big, got [%T]", sk)
}
iipk, ok := ipk.(*IssuerPublicKey)
if !ok {
return nil, errors.Errorf("invalid issuer public key, expected *IssuerPublicKey, got [%T]", ipk)
}
if len(nonce) != cryptolib.FieldBytes {
return nil, errors.Errorf("invalid issuer nonce, expected length %d, got %d", cryptolib.FieldBytes, len(nonce))
}
rng := cr.NewRand()
credRequest := cryptolib.NewCredRequest(
isk.E,
nonce,
iipk.PK,
rng)
return proto.Marshal(credRequest)
}
// Verify checks that the passed credential request is valid with the respect to the passed
// issuer public key.
func (*CredRequest) Verify(credentialRequest []byte, ipk handlers.IssuerPublicKey, nonce []byte) (err error) {
defer func() {
if r := recover(); r != nil {
err = errors.Errorf("failure [%s]", r)
}
}()
credRequest := &cryptolib.CredRequest{}
err = proto.Unmarshal(credentialRequest, credRequest)
if err != nil {
return err
}
iipk, ok := ipk.(*IssuerPublicKey)
if !ok {
return errors.Errorf("invalid issuer public key, expected *IssuerPublicKey, got [%T]", ipk)
}
err = credRequest.Check(iipk.PK)
if err != nil {
return err
}
// Nonce checks
if len(nonce) != cryptolib.FieldBytes {
return errors.Errorf("invalid issuer nonce, expected length %d, got %d", cryptolib.FieldBytes, len(nonce))
}
if !bytes.Equal(nonce, credRequest.IssuerNonce) {
return errors.Errorf("invalid nonce, expected [%v], got [%v]", nonce, credRequest.IssuerNonce)
}
return nil
}